Nishi system theories are characterized by the idea that the while the human bone structure and positioning of the internal organs are basically the same as in mammals that walk on four legs, human beings have adopted a different upright two-legged life style. This dissonance causes certain structural strains on the human bone structure.
As people engage in daily activities, the spinal vertebrae experience subluxations (partial misalignment) that can adversely affect the function of various parts of one's body, and ultimately one's health. It happens every day due to the upright position of our bodies.
How does this affect you? Your nervous system controls and coordinates all the functions of your body. If there is interference with the signals traveling over nerves, parts of the body will not get the proper nerve messages and will not be able to function at 100% of their innate abilities. In other words, some part of the body will not be working properly.
To be healthy, it is essential that the nervous system functions properly and free from any interference caused by subluxations.
Katsudzo Nishi developed efficient approaches to compensate for these structural disturbances though the series of exercises.
Another principle of Nishi system is based on theory that the network of capillaries play a role of the driving force for the blood flow and also act as the "second heart".
This theory was first mentioned in the works of Malpighi, the Italian scientist who later in life became the world greatest authority in histology.
Many theories of Chinese medicine also state that proper circulation of the blood plays a major role in an individual's state of health.
Nishi calls this second principle "capillarity."
Based on the structure of the human network of arteries and veins, Nishi supported Malpighi's capillaries theory and added a theory that the capillaries provided the true driving force of the circulatory system. And, in order to compensate for the obstruction of circulation in the four limbs resulting from the humans vertical posture, he developed the another series of exercises that compensate poor circulation.
Besides these exercises, Nishi also recommended using hard, half–cylinder pillow, to keep the cerebral vertebrae (the neck part of the spine) in the ideal position, and a flat sleeping platform (flat board) designed to do the same for the vertebrae of the spinal column.
Modern medical science is apt to look at deceases not in general, but in the local light.
According to Nishi, if the spinal column is allowed to become straight by lying on a flat bed, any strain or compression caused by the upright posture on the motor nerves could be alleviated.
"Your health is greatly affected by the state of your spine. Your body will strive if your have a good circulation" he wrote in one of his books.